Recyclerview, I can't get item view with getChildAt(position). Null object reference

Question

I am using a recyclerView inside my navigation drawer and I am using this library Twoway-view to get click and selection support.

It works perfectly and I can change the color of the text and the icons without problems inside OnClick method for each position:

itemClickSupport.setOnItemClickListener(new ItemClickSupport.OnItemClickListener() { @Override public void onItemClick(RecyclerView parent, View view, int position, long id) { TypedValue typedValue = new TypedValue(); MainActivity.this.getTheme().resolveAttribute(R.attr.colorAccent, typedValue, true); final int color = typedValue.data; //TODO Icon and text colors for (int i = 0; i < drawerTitles.length; i++){ if (i == position){ ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.imageViewDrawerIcon); TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.textViewDrawerItemTitle); imageViewDrawerIcon.setColorFilter(color); if(Build.VERSION.SDK_INT > 15){ imageViewDrawerIcon.setImageAlpha(255); }else{ imageViewDrawerIcon.setAlpha(255); } textViewDrawerTitle.setTextColor(color); RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(i).findViewById(R.id.relativeLayoutDrawerItem); relativeLayoutDrawerItem.setFocusableInTouchMode(true); }else{ ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.imageViewDrawerIcon); TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.textViewDrawerItemTitle); imageViewDrawerIcon.setColorFilter(getResources().getColor(R.color.md_text)); if(Build.VERSION.SDK_INT > 15){ imageViewDrawerIcon.setImageAlpha(138); }else{ imageViewDrawerIcon.setAlpha(138); } textViewDrawerTitle.setTextColor(getResources().getColor(R.color.md_text)); RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(i).findViewById(R.id.relativeLayoutDrawerItem); relativeLayoutDrawerItem.setFocusableInTouchMode(false); } } //TODO Fragments (closedrawers before setfragment) final Handler handler = new Handler(); handler.postDelayed(new Runnable() { @Override public void run() { // Do something after some time } }, 250); mDrawerLayout.closeDrawers(); } });

The problem is that I want to access to the first item like in that method, but before it (to set the first item selected, with different color, etc).

But I get a crash (null reference) when I try to get the first item outside OnClick method:

ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(0).findViewById(R.id.imageViewDrawerIcon);

All code:

// Setup RecyclerView inside drawer recyclerViewDrawer = (RecyclerView) findViewById(R.id.recyclerViewDrawer); recyclerViewDrawer.setHasFixedSize(true); recyclerViewDrawer.setLayoutManager(new LinearLayoutManager(MainActivity.this)); ArrayList<DrawerItem> drawerItems = new ArrayList<>(); final String[] drawerTitles = getResources().getStringArray(R.array.drawer); final TypedArray drawerIcons = getResources().obtainTypedArray(R.array.drawerIcons); for (int i = 0; i < drawerTitles.length; i++) { drawerItems.add(new DrawerItem(drawerTitles[i], drawerIcons.getDrawable(i))); } drawerIcons.recycle(); adapterDrawer = new DrawerAdapter(drawerItems); recyclerViewDrawer.setAdapter(adapterDrawer); // Here is the problem ImageView imageViewDrawerIcon2 = (ImageView) recyclerViewDrawer.getChildAt(0).findViewById(R.id.imageViewDrawerIcon); // RecyclerView item listener. ItemClickSupport itemClickSupport = ItemClickSupport.addTo(recyclerViewDrawer); itemClickSupport.setOnItemClickListener(new ItemClickSupport.OnItemClickListener() { @Override public void onItemClick(RecyclerView parent, View view, int position, long id) { TypedValue typedValue = new TypedValue(); MainActivity.this.getTheme().resolveAttribute(R.attr.colorAccent, typedValue, true); final int color = typedValue.data; //TODO Icon and text colors for (int i = 0; i < drawerTitles.length; i++){ if (i == position){ ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.imageViewDrawerIcon); TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.textViewDrawerItemTitle); imageViewDrawerIcon.setColorFilter(color); if(Build.VERSION.SDK_INT > 15){ imageViewDrawerIcon.setImageAlpha(255); }else{ imageViewDrawerIcon.setAlpha(255); } textViewDrawerTitle.setTextColor(color); RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(i).findViewById(R.id.relativeLayoutDrawerItem); relativeLayoutDrawerItem.setFocusableInTouchMode(true); }else{ ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.imageViewDrawerIcon); TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.textViewDrawerItemTitle); imageViewDrawerIcon.setColorFilter(getResources().getColor(R.color.md_text)); if(Build.VERSION.SDK_INT > 15){ imageViewDrawerIcon.setImageAlpha(138); }else{ imageViewDrawerIcon.setAlpha(138); } textViewDrawerTitle.setTextColor(getResources().getColor(R.color.md_text)); RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(i).findViewById(R.id.relativeLayoutDrawerItem); relativeLayoutDrawerItem.setFocusableInTouchMode(false); } } //TODO Fragments (closedrawers before setfragment) final Handler handler = new Handler(); handler.postDelayed(new Runnable() { @Override public void run() { // Do something after some time } }, 250); mDrawerLayout.closeDrawers(); } });

Possible duplicate of RecyclerView - Get view at particular position — Kaibo
– Kaibo, Commented Nov 1, 2019 at 12:58

Dmitriy · Accepted Answer · 2016-04-12 10:16:38Z

20

In my case it,is work like a charm

View viewItem = recycleView.getLayoutManager().findViewByPosition(position); View icon = viewItem.findViewById(R.id.view);

answered Apr 12, 2016 at 10:16

Dmitriy

3564 silver badges9 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Patriotic Over a year ago

Gives warning "Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView"

user25 Over a year ago

it returns null

user25 Over a year ago

Seems it works only if item is visible right now, useless. Even if I call layoutManager.scrollToPosition(position) before calling findViewByPosition(position) it still doesn't work

Community · Accepted Answer · 2017-05-23 12:34:18Z

I solved finally with this (source):

recyclerViewDrawer.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() { @Override public void onGlobalLayout() { ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(0).findViewById(R.id.imageViewDrawerIcon); TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(0).findViewById(R.id.textViewDrawerItemTitle); imageViewDrawerIcon.setColorFilter(color); if (Build.VERSION.SDK_INT > 15) { imageViewDrawerIcon.setImageAlpha(255); } else { imageViewDrawerIcon.setAlpha(255); } textViewDrawerTitle.setTextColor(color); RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(0).findViewById(R.id.relativeLayoutDrawerItem); relativeLayoutDrawerItem.setFocusableInTouchMode(true); // unregister listener (this is important) recyclerViewDrawer.getViewTreeObserver().removeGlobalOnLayoutListener(this); } });

By the way, if someone have a better solution I would like to know it.

We're still getting some instances of getChildViiew(0) being null with this approach. I personally can't reproduce it. Using setAdapter triggers the child view inflation so ideally there would be a callback that is called when the child view is inflated and added to the RecyclerView

Hermandroid · Accepted Answer · 2017-05-04 14:35:15Z

8

This worked for me.

recyclerView.post(new Runnable() { @Override public void run() { View viewItem = recycleView.getLayoutManager().findViewByPosition(position); View icon = viewItem.findViewById(R.id.view); } });

answered May 4, 2017 at 14:35

Hermandroid

2,2004 gold badges30 silver badges35 bronze badges

2 Comments

Peterdk Over a year ago

Nice, this worked perfectly for getting the displayed children and viewholders using getChildAt() and getChildViewHolder()

Kilves Over a year ago

Of note is that you can't manipulate many UI elements with this, since you're working from a different thread. You'll have to set up inter-thread communication.

AllDayAmazing · Accepted Answer · 2016-02-10 07:44:37Z

I would use findViewHolderForAdapterPosition() or findViewByPosition() instead to find the root view at that index. The way you ensure the data is loaded is up to you, however.

Kaibo · Accepted Answer · 2019-10-21 13:37:46Z

findViewByPosition is a method of LayoutManager, which works with all LayoutManagers.

So you can use recycleView.getLayoutManager() and findViewByPosition(pos).

Also recyclerView.findViewHolderForAdapterPosition(pos) works too.

For more information, look at this RecyclerView - Get view at particular position

Anant Shah · Accepted Answer · 2023-07-20 18:23:18Z

You can get ItemView from recyclerView's holder using below code:

val holder = yourRecyclerView.findViewHolderForAdapterPosition(position) if (holder != null) { val rootView = holder.itemView //do your code here }

Collectives™ on Stack Overflow

Recyclerview, I can't get item view with getChildAt(position). Null object reference

6 Answers 6

3 Comments

1 Comment

2 Comments

Comments

Comments

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

3 Comments

1 Comment

2 Comments

Comments

Comments

Comments

Linked

Related